Coverage Tests not reporting Encoder-Coverage

This is a split-off from #1948 (closed):

There are no encoder coverage test data reported. Looking at the artifacts it's apparent that the encoder scripts are called with IVAS_dec as encoder executable, see e.g., https://sa4.3gpp.org/-/audio/ivas-basop/-/jobs/534022/artifacts/report-enc.html.

See also https://forge.3gpp.org/rep/ivas-codec-pc/ivas-codec-ci/-/blob/main/main-basop.yml, line 2202:

python3 -m pytest --tb=no tests/codec_be_on_mr_nonselection --encoder_only -v  --html=report-enc.html --self-contained-html --junit-xml=report-junit-enc.xml -n auto --testcase_timeout $testcase_timeout --dut_encoder_path IVAS_dec || exit_code_enc=$?

which calls the scripts with --dut_encoder_path IVAS_dec